server: basic graphql thread show, no body support yet.

notmuch/src/lib.rs

@@ -561,7 +561,10 @@ impl Notmuch {
         Ok(BufReader::new(child.stdout.take().unwrap()).lines())
     }
 
-    // TODO(wathiede): implement tags() based on "notmuch search --output=tags '*'"
+    pub fn files(&self, query: &str) -> Result<Lines<BufReader<ChildStdout>>, NotmuchError> {
+        let mut child = self.run_notmuch_pipe(["search", "--output=files", query])?;
+        Ok(BufReader::new(child.stdout.take().unwrap()).lines())
+    }
 
     fn run_notmuch<I, S>(&self, args: I) -> Result<Vec<u8>, NotmuchError>
     where